wallet: Move discard feerate fetching to CreateTransaction

Instead of fetching the discard feerate for each SelectCoinsMinConf
iteration, fetch and cache it once during CreateTransaction so that it
is shared for each SelectCoinsMinConf through
coin_selection_params.m_discard_feerate.

Does not change behavior.

Github-Pull: #21083
Rebased-From: bdd0c2934b7f389ffcfae3b602ee3ecee8581acd

1 files changed, 5 insertions, 4 deletions

diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index b1951c0c3d..a3216a33ae 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -2363,7 +2363,7 @@ bool CWallet::SelectCoinsMinConf(const CAmount& nTargetValue, const CoinEligibil
     std::vector<OutputGroup> utxo_pool;
     if (coin_selection_params.use_bnb) {
         // Calculate cost of change
-        CAmount cost_of_change = GetDiscardRate(*this).GetFee(coin_selection_params.change_spend_size) + coin_selection_params.effective_fee.GetFee(coin_selection_params.change_output_size);
+        CAmount cost_of_change = coin_selection_params.m_discard_feerate.GetFee(coin_selection_params.change_spend_size) + coin_selection_params.effective_fee.GetFee(coin_selection_params.change_output_size);
 
         // Filter by the min conf specs and add to utxo_pool and calculate effective value
         for (OutputGroup& group : groups) {
@@ -2805,7 +2805,8 @@ bool CWallet::CreateTransactionInternal(
             CTxOut change_prototype_txout(0, scriptChange);
             coin_selection_params.change_output_size = GetSerializeSize(change_prototype_txout);
 
-            CFeeRate discard_rate = GetDiscardRate(*this);
+            // Set discard feerate
+            coin_selection_params.m_discard_feerate = GetDiscardRate(*this);
 
             // Get the fee rate to use effective values in coin selection
             coin_selection_params.effective_fee = GetMinimumFeeRate(*this, coin_control, &feeCalc);
@@ -2924,7 +2925,7 @@ bool CWallet::CreateTransactionInternal(
                     // Never create dust outputs; if we would, just
                     // add the dust to the fee.
                     // The nChange when BnB is used is always going to go to fees.
-                    if (IsDust(newTxOut, discard_rate) || bnb_used)
+                    if (IsDust(newTxOut, coin_selection_params.m_discard_feerate) || bnb_used)
                     {
                         nChangePosInOut = -1;
                         nFeeRet += nChange;
@@ -2976,7 +2977,7 @@ bool CWallet::CreateTransactionInternal(
                     if (nChangePosInOut == -1 && nSubtractFeeFromAmount == 0 && pick_new_inputs) {
                         unsigned int tx_size_with_change = nBytes + coin_selection_params.change_output_size + 2; // Add 2 as a buffer in case increasing # of outputs changes compact size
                         CAmount fee_needed_with_change = coin_selection_params.effective_fee.GetFee(tx_size_with_change);
-                        CAmount minimum_value_for_change = GetDustThreshold(change_prototype_txout, discard_rate);
+                        CAmount minimum_value_for_change = GetDustThreshold(change_prototype_txout, coin_selection_params.m_discard_feerate);
                         if (nFeeRet >= fee_needed_with_change + minimum_value_for_change) {
                             pick_new_inputs = false;
                             nFeeRet = fee_needed_with_change;